Refrigeration system



Nov. 8, 1966 J. T. BYRON REFRIGERATION SYSTEM 2 Sheets-Sheet l Filed March 17, 1964 @M f W J ....lfl... ...I ...2....1

1li.' ff 'uit .||...|r... 1... 1;... I... 'vh .11.1.19 :tlrlll LII IIKL Nov. 8, 1966 J. T. BYRON REFRIGERATION SYSTEM 2 Sheets-Sheet 2 Filed March 17, 1964 INVENTOR J'OH/V 7T' VRC/V ,4 7' rop/vins United States Patent O 3,283,524 REFRIGERATION SYSTEM John Thomson Byron, 28 Tutela Heights Road, Brantford, Ontario, Canada Filed Mar. 17, 1964, Ser. No. 352,526 5 Claims. (Cl. (S2- 115) This application is a continuation-in-part of my prior application Serial No. 241,937, tiled December 3, 1962, now abandoned.

This invention relates to refrigeration systems and particularly to commercial `systems of the expansion valve or capillary tube type.

lt isa further object of the invention to provide such a refrigeration system which utilizes a ow controlling device having a larger opening than has been heretofore thought possible for van equivalent capacity system.

It is a further object of the invention to provide a refrigeration system which utilizes a compressor of much `less capacity for refrigeration spaces of the same size.

It is a further object of the invention to provide such `a refrigeration system wherein the compressor is operated at a much lower .head pressure, and -a much higher suction pressure.

It is an object of the invention to provide a refrigeration system which has a greater efficiency than has been Aheretofore possible with conventional systems.

It is a further object of the invention to provide such a system which is self-defrosting during the o cycle when refrigerating a space at above 32 F. and defrosts in a much shorter time than conventional systems utilizing some conventional defrosting arrangement when refrigerating a space below 32 F.

It is a further object of the invention to provide such a system which produces a mist type oiling for all internal parts of the compressor-pistons, valves, seals, crankshaft, wrist-pins, eccentrics, and bearings.

It is a further object of the invention to provide such a refrigeration system which is less likely to slugging of the compressor than conventional systems.

It is a further object of the invention to provide such a system which makes it possible to use a motor compressor unit which is less than half in size, less than half in cost, and less than 'half in power requirements than motor compressors heretofore thought to be needed for the same refrigerating capacity.

It is a further object of the invention to provide a refrigeration system which operates on a substantially lower pressure differential between the high side and the low side than has heretofore been thought possible.

Basically, the refrigeration system embodying the invention comprises a compressor, a condenser connected to the compressor, a liquid receiver connected to the condenser, a flow controlling device having a relatively large restriction preferably in the form of a restrictive tube or special capillary connected to the liquid receiver, a continuous coil evaporator connected to the restrictive tube, and an accumulator connected to the evaporator and to the inlet of the compressor. The accumulator has a volumetric capacity equal to or greater than the evaporator. When a tube is used as a restrictive device, it is much shorter in length and greater in cross-sectional area than conventional capillaries for equivalent capacity refrigeration systems. A heat exchanger may optionally be provided between the accumulator and compressor in heat exchange relationship tothe restrictive device. It has been found that such a system permits the use of a compressor of much less capacity for the same refrigerating requirements. The compressor operates as a result of the system at a much lower head pressure and a higher back pressure so that the compressor does not become ytures above 32 F.

iCC

so hot but, on the contrary, can be readily touched by hand. The system is completely selfdefrosting during the off cycle when used to refrigerate spaces to tempera- It has further been found that in such a system there is less likelihood of slugging. In addition, it appears that a fine mist of oil is passed to the compressor to lubricate the compressor so that the compressor tends to operate more uniformly.

While my system requires a-bout three times the amount of refrigerant as that required in comparable systems, the combination of a relatively large restrictor, an accumulator, and a low pressure differential, results in an evaporator which, in operation, has substantially all its internal wall surface coated with liquid refrigerant uniformly throughout its length.

In the drawings:

FIG. l is a diagrammatic view of a refrigeration system embodying the invention.

FIG. 2 is a part sectional View of a combined restrictive device in the form of a tube, accumulator, heat exchanger and oil separator which may be used in the sy-stem shown in FIG. l.

FIG. 3 is a sectional view taken along the line 3 3 in FIG. 2.

FIG. 4 is a part sectional view of a modied type of combined restrictive device in the form of a tube, accumulator, heat exchanger and oil separator which may ybe used in the system shown in FIG. 1.

Referring to FIG. l, the refrigeration system embodying the invention comprises a compressor 10 which has an inlet and an outlet. A condenser 11 is connected to the outlet by a line 12 and a liquid receiver 13 is connected to the outlet of the condenser by a line 14. The outlet of the liquid receiver is, in turn, connected to the inlet of a flow controlling device in the form of -a tube or special capillary 15 by a line 15. The outlet of the restrictive tube 15 is connected to the inlet of the evaporator 17. The outlet of the evaporator is, in turn, connected to the inlet of an accumulator 22 by a line 19 and the outlet of the accumulator 22 is connected to the inlet of the compressor 10 by a line 2t). Optionally, a heat exchanger 21 is provided in the line 20.

The accumulator 22 has a volumetric capacity equal to or greater than the evaporator. The liquid receiver 13 has a volumetric capacity sufficient to keep the condenser 11 free of most liquid at all times. My ow control device such as a restrictive tube or special capillary 15 is of larger capacity than conventional capillaries for use with comparable systems, that is, comparable size compressors. More specifically, the restrictive tube 15 is preferably much shorter in length or much greater in diameter than conventional capillaries. With this combination of a large flow control unit that ilows liquid refrigerant into the evaporator, the evaporator, which is substantially a flooded continuous coil type, and the accumulator, the system requires a charge of refrigerant substantially three times that required in conventional systems of comparable refrigerating capacity.

In my system with a charge of refrigerant double and preferably triple in weight of the normal charge in the system, the compressed substantially saturated gas, as later understood, from compressor 10 flows through line 12 to the condenser 11 and collects in the receiver 13 as a liquid. From the receiver 13, the liquid under relatively low head pressure is fed to the restrictive tube 15 which is at least twice as large as the conventional capillary heretofore thought to be needed for a system of comparable size. The liquid from the receiver 13 is fed to and through the restrictive tube 15 as a continuous and uninterrupted mass of liquid. From the restrictive tube 15 the liquid ows into the continuous coil evaporator 17 where there will be some liquid refrigerant present throughout'its entire length and, in fact, some liquid will iiow into the accumulator 22. There will be liquid in the bottom of each coil of the evaporator and there will be liquid backing substantially all the surfaces of the evaporator. Some compressed liquid refrigerant will be exploding throughout the length of the continuous tube evaporator so that the refrigerating effect is substantially uniform from inlet to outlet. Because the refrigerant in the evaporator is in the form of a highly saturated vapor, and the internal surfaces are backed with liquid, the heat transfer is at a maximum etiiciency and results in an eiiiciency about tive times as great as that obtained when the refrigerant in the evaporator is a dry gas. A highly but slightly less saturated vapor passes from the evaporator 17 to the accumulator 22 which collects oil and liquid refrigerant and prevents the liquid refrigerant from entering the suction pipe of the compressor 10. From the accumulator 22 the highly but slightly less saturated vapor minus any slugs of liquid is returned to the compressor 10.

Due to the fact that there is only a relatively moderate change of state or condition from a relatively low pressure liquid in the high side to a lower pressure saturated vapor in the entire low side, the back pressure remains relatively high and the head pressure remains relatively low when compared to prior art systems. Because other systems change the liquid to a dry gas of relatively low saturation, more work is required by the compressor to return the refrigerant to the liquid state. Such additional work requires more energy and develops more heat. Since less heat is required in my system, the head remains relatively cool and can be touched by hand.

Expansion valves which are, in essence, throttle valves, cause heat due to molecular friction. Standard capillary tubes, wherein the refrigerant changes to vapor within the capillary, produce molecular friction which in turn produces heat. This heat is added to the evaporator and must be dissipated to the condenser. The larger bore and shorter length of the flow controlling device of the present invention does not produce extra heat, thus a smaller motor compressor unit will produce a given refrigerating eiect.

Because of the increased efficiency of my system, it is possible to use a motor compressor unit which is substantially, less in capacity for the same refrigerating results. Since the cost of weight of motor compressors constitutes -the greatest portion of the cost in Weight of a refrigeration system, the resultant savings in cost and weight by utilizing my system are at least one half of present refrigeration systems.

When the system is being used to refrigerate spaces at above 32 F. and the compressor stops on the off cycle, hot liquid Freon continues to ow easily through the relatively large special capillary into the evaporator and effectively defrosts the coil in approximately ten percent of the time required using auxiliary defrosting devices.

Due to the fact that the defrost period is relatively short, the space being refrigerated has less opportunity to rise in temperature and therefore there is less overall load on the motor compressor unit. In addition, the capacity of the motor compressor unit is available for refrigerating a greater portion of the time.

Where the system is used for refrigerating spaces below 32 F., the flow of hot liquid refrigerant during the oi cycle tends to minimize the need for defrosting and, also, assist in the defrosting when an auxiliary defrosting device is used. As a result, a system used for maintaining a space below 32 F. requires less frequent defrosting.

Since the refrigerant in the cooling coil (evaporator) is in the form of a highly saturated vapor, which has a greater capacity for absorbing heat, a smaller temperature diierential is maintained between the cooling coil and the air in the space being cooled. As a result, very little frost accumula-tes on the evaporator thus shortening the defrost period and also this small temperature difference and little frost accumulation results in very little moisture removal from the products, such as food, being cooled, thus maintaining a very high relative humidity of to 98%. In this way, food can be kept fresh and moist much longer than in conventional coolers of the present day.

Medium pressure vapor is throught into the compressor suction side. This vapor yconsists of a mixture of Freon globules of vapor and globules or droplets of oil interspersed and interdissolved. The pressure in the crankcase is less than in the suction line outside the compressor and due to the decreased pressure in the crankcase, the Freon and oil droplets expand and explode, thus causing an oil mist to lubricate the pistons and cylinder walls and the wrist pins, cranksha-"fts, eccentrics, valve discs, reeds, and al1 moving internal parts of the compressor as the mixture moves through on its way to the condenser. This assures long trouble-free operation of the compressor.

As shown in FIGURE 1, the return line 23 from heat exchanger 21 passes through an enlarged portion 24 of the outlet 12 so that the returning vapor is in heat exchange relationship with the compressed refrigerant passing out of the compressor 10.

Due to the fact that with my method the head pressure remains relatively low and therefore the temperature of the discharge vapor keeps far below the critical temperature for the Freons (that is: 205 F. for Freon 22 and 233 F. for Freon 12). The critical temperature for a vapor is that temperature above which it is impossible to return the vapor to a liquid regardless of how great pressure is put on it.

Therefore, with other methods, the Vapor reaches far higher than critical temperatures and will not liquefy, and thus causes so called ash gas in the liquid line.

My method uses vapor, i.e., wet in the -form of fog and/or liquid to carry heat from the area to be cooled and discharges this heat at the condenser. Thus, the heat carrying power is many times greater using liquid and vapor by my method than by dry gas using other methods. v

Due to the fact that my'method operates with a small temperature differential between evaporator and the surrounding air, the relative humidity of the refrigerated space is held very high-near the dew point-regardless of the temperature. Thus, .there is very little dessicating of stored products-a feature Ivery desirable and, by present methods, very costly and diiiicult to obtain.

The size of the restrictive device used in my system is much larger than has been heretofore thought possible for restrictions such as capillaries in comparable systems utilizing comparable size compressors. Thus, it has heen conventional to use with a two horsepower compressor a capillary, for example, having an internal diameter of 0.050 and eleven foot length. In accordance with my `invention, for a two horsepower compressor, a restrictive tube is used which is 0.100 inch internal diameter and four feet long. The lengths and bores of the tubes, vary according to their applications but when compared with standard capillary tubes used to achieve similar results, are much shorter in length and/ or much larger in bore than those presently used to obtain similar B.t.u. removal, 1.e., similar refrigerating effects. The restrictive eiect of the restrictive device used in my system is less than one half the restrictive effect of capillaries and other expansion devices heretofore used. Even in household refrigeration systems when capillaries are usually used with an internal diameter of 0.0156 or less and substantial length, in my system, it is desirable to keep the internal diameter of the restrictive device above 0.020 inch and with a much lesser length.

An example of a system and the results achieved is as follows: A combined compressor, condenser and liquid receiver, fan driven, air cooled and of one-half horsepower was connected to an accumulator having a capacity greater than the evaporator. The restrictive device was in the form of a ltube having an internal diameter of 0.050 inch and three to four feet in length. This arrangement was used to cool a Walk-in refrigeration enclosure which was fteen feet by nine feet by ten feet and had a concrete .oor and four inch .cork board walls and ceiling The evaporator used was fifty-five inches in length of :ive-eighths inch tubing two tubes wide and three tubes high, having iins one-half inch apart of a size three by three inches slipped on the tubes.

When such a system was operated, it was ifound that the one-half horsepower compressor was able to hold the temperature of the enclosure at 34 F. with intermittent operation.

When la similar system was used, utilizing a thermostatic expansion valve, compressor, condenser, and receiver, it was found that a two horsepower compressor condenser was needed to maintain the temperature at 35 F. with the compressor operating at all times when used in the same box.

The operation of the system can also be more fully understood by the following example:

A pail of boiling (212 F.) water of fifty pounds lcapacity was inserted in a 22 cubic foot enclosure utilizing the refrigeration system of the present invention which system had a one-quarter horsepower compressor which maintained the enclosure at 33 F. The ambient temperature outside the enclosure and surrounding the unit was 80 F. Within forty minutes, the temperature of the enclosure reached 50. In the next Fforty minutes, the temperature of the enclosure (refrigerator) went -down to 33 which was the ytemperature of the air in the enclosure.

Subsequently, a similar enclosure was connected to a conventional system utilizing one-.third horsepower compressor, and a thermostati'c expansion valve. With fifty pounds of boiling water in position in the enclosure, it was found that it took ninety minutes for the system to reach 52-53 degrees and one hundred and twenty minutes more to go down to 33 F.

A comparison of the above two systems indicated that the dome of Vthe compressor in the system embodying the invention was Warm and could be readily touched by hand whereas, the dome of the compressor of the prior art was so hot that it could not be touched by hand.

It was also found that the system was self-defrosting on the off cycle and no frost accumulated.

An improved eiciency of the system heretofore described is achieved by combining a restrictive tube, accumulator, heat exchanger and an oil separatingfdevice in a single enclosure such as shown in FIG. 2. As shown in FIG. 2, `a container 2S encloses a cylinder 25a which, in turn, encloses the restrictive tube or special capillary 26. Liquid refrigerant from the liquid receiver passes through pipe 16 land screen 16a to the interior of cylinder 25a. The liquid refrigerant then enters restrictive tube 26 through screen 26a. The container 25 itself forms the accumulator to which the refrigerant ows fro-m the evaporator 17, some liquid refrigerant collecting in the bottom of the cylinder 25a. The refrigerant from the evaporator comes into heat exchange relationship with the cylinder 25a and restrictive tube 26 -so that, in effect, a heat exchanger is produced. rl`he refrigerant vapor then passes by successive baflies 27 and into the top of an outlet tube 28 to the compressor. The passage past the baiiles 27 separates any oil globules from the refrigerant and `the oil collects at the bottom of the container 25 and is removed as drops through a small oil take off 28a. The Freon liquid and vapor moves with sufficient velocity through the evaporator and accumulator to sweep oil globules alon-g with it instead of allowing the globules to fall out and collect as a liquid in the lowside as is the case where there is insufficient refrigerant vapor velocity to displace oil in the lowside. Thus, the refrigerant passing to the outlet 28 contains oil mostly in the misty form which bathes the compressors internal parts, and effectively lubricates all internal parts-*even the valve reeds or discs in the discharge plate, which, with present systems, after a few weeks operation, are invariably found dry and Worn. The process is continuous and thus continuous lubrication is provided to all internal moving pa-rts.

In the combined unit shown in FIG. 4, container 25 encloses and forms `the accumulator'in which the restrictive tube or special capillary 26 is positioned. The refrigerant from the liquid receiver passes from tube 16 through the restrictive device 26 and thereafter through tube 18 to the evaporator. The refrigerant from the evaporator passes into the container 25 through tube 19" and is subjected to the baflles 27 as in the previous combined unit shown in FIGS. 2 and 3. By this arrangement, the enclosure 25 serves the dual function Iof `an accumulator and a heat exc-hanger with the restrictive tube 26.

Although I do not wish to be bound by the theory involved, in my opinion, the beneficial advantages obtained by the present invention are due to an operation of the system at lower pressure so that less heat is lost Iby radiation and a higher efficiency is achieved, due Ialso to the fact that vapor and/or liquid transports many times the B.t.u.s that -a similar volume of dry gas will transport. My method uses vapor and/or liquid refrigerant to remove the B.t.u.s from the sp-ace to be cooled, whereas the prior art systems use relatively dry gas to remove the B.t.u.s and thus their carrying capacity is much less.

The following is the thermodynamic calculations showing the proper B.t.u. availability in a refrigeration cycle.

T-temperature P-pressure With T and P constant, we have W= -pv and the condition of equilibrium becomes If energy U and volume V are independent variable, then the entropy is the characteristic function and we nd directly from the equation:

and hence p and U can be found as functions of T and P.

Likewise, if V and T are chosen as independent variable, then the free ener-gy F is the characteristic function and F W vt T, then we have the If p and T are chosen as independent variables, then the characteristic function is n follows that:

dU+ pava-mp Et U+ PV T P T2 If gb is a known function of p and T, then We have dit:

Hence and and

R.P.M.=1750 Displacement=5-78 cubic inch per revolution Time=60 minutes or 1 hour At F. vapor density of F 12 is .2557 lbs/cu. ft.

Latent Heat at 40 F.=73.50 B.t.u. per lb. Therefore: enthalpy per H.P. per hour for 5.78X1750X60X.2557X73.50 1728 6600.72 B.t.u.lhr. per' H.P

Tecumseh rating for 1 H.P. at 40 F. is 2170 B.t.u./hr.

Therefore, my system gives 6600.72/2170.00=3+ or three times the refrigerating eect obtained from present systems. One of the main reasons is the fact that cold liquid and vapor is present in the evaporator using my device. Thus, the temperature difference between the refrigerant in the evaporator and the air in the room being cooled is very small perhaps less than 5 F., i.e., it is not necessary to have the metal of the evaporator much lower in temperature than the temperature of the air or product in the refrigerated room. Also, due to mist oiling of the valves and pistons and due to low head pressure, there is not the usual heat from friction or the llSual heat of compression.

Similarly, for Freon 22 as per Tecumseh specifications: Displacement-:3.59 cubic inches. At 40 F., vapor density of F 22 is .3050 1b./cu. Latent heat at 40 F.=100.46 B.t.u. per lb. R.P.M.=1750.

Total refrigerating ei`eet= 3.59 X 1750 X 60 X 0.3050 X 100.46

6685.7 B.t.u./hL per H.P.

Tecumseh rating for l H.P. is 1920 B.t.u./hr. per H.P.

As heretofore discussed, in systems embodying my invention, the head pressure is substantially lower and the back pressure is substantially higher than in conventional refrigerating systems. As a general rule, if systems embodying my invention are compared with comparable systems utilizing the same size compressors, the head pressure in my system is less than half the head pressure in conventional systems and the back pressure in my system is more than double the back pressure in conventional systems, Moreover, if the same size compressors are used, my system produces a much greater refrigerating capacity as heretofore described.

As an example, a system embodying my invention utilizing a two horsepower compressor for refrigerating a space above 32 F. may have a head pressure of approximately pounds per square inch and a back pressure of approximately 15 pounds per square inch. This may be contrasted to a conventional refrigerating system utilizing a two horsepower compressor which under the same conditions may have a head pressure of approximately pounds plus per square inch and a back pressure of approximately 5 pounds plus per square inch.

It can thus be seen that there has been provided in accordance with my invention a refrigeration system which has a greater eiciency than has heretofore been possible with conventional systems. In accordance with my invention a compressor is used having a capacity much less than has been heretofore thought necessary for refrigerating spaces of the same size. The compressor is operated at a substantially lesser head pressure and a much higher suction pressure. The system is selfdefrosting during the olf cycle when refrigerating a space to temperatures above 32 F. and defrosts in a much shorter time than conventional systems utilizing some defrosting arrangement when refrigerating a space to a temperature below 32 F. Furthermore, the system provides a mist type oiling for all internal parts of the compressor.

The refrigerating system embodying my invention is thus more efficient and less costly than prior art systems.

In a standard system of the prior art, it has been customary where, for example, a 20 F. air temperature is desired adjacent an evaporator coil, to design the system so that the temperature of the evaporator coil is about 0 F. In a system embodying my invention, in order t-o have a 20 F. air temperature adjacent the evaporator coil, it is recommended that the temperature of the evaporator coil be 15 F. Similarly, in walk-in refrigerator boxes maintained at a temperature of 35 F. it is conventional, utilizing a standard system, to use an evaporator coil which is at a temperature of 15 F. For a comparable temperature of 35 F. in the Walk-in box, in my system, the evaporator coil is recommended to be at 32 F.

Summarizing the most important features of my invention:

(1) The combination of a relatively low pressure differential between the high side and the low side.

(2) A flow control device which feeds the liquid refrigerant to the evaporator as a liquid refrigerant.

(3) An accumulator that has a volumetric capacity equal to the condenser or evaporator.

(4) In the operation of the system, because of the combination between the large flow control and the accumulator, one has what might be called a continuous flooded evaporator, in that substantially all of the internal surfaces of the coil are backed with liquid, substantially uniformly throughout its length, with refrigerant exploding into gas bubbles throughout its length'.`

(5) The accumulator will be partially filled with refrigerant liquid.

(6) During off cycles the relatively large control unit will feed hot refrigerant liquid to the evaporator.

(7) Because of the combination of the relatively large flow control unit, wet surface evaporator, and accumulator, my system requires initial charging of approximately, preferably, three times the amount of refrigerant used in a conventional system of comparable refrigerating effect.

(8) Furthermore, the system permits a misting type oiling for all internal parts of the compressor.

(9) Because my system puts more liquid through the flow control device than a standard system, the -ow rate of liquid and gas throughout my entire system is much faster than in standard systems using the same size compressor.

(10) Although some oil droplets may collect at the bottom parts of the evaporator and the bo-ttom of the accumulator when the system is shut olf, when in operation, the oil droplets will be swept clear and into the compressor.

What I claim is:

1. The method of improving the thermodynamic efficiency of refrigeration systems of the restrictive device type Iand utilizing a continuous type evaporator and accumulator which comprises charging the system with at least twice the normal amount of refrigerant used with such a system of the same refrigerating capacity,

continuously circulating said abnormal volume through the system,

decreasing the :restrictive effect of the restrictive device to at least one half that of the standard type for an evaporator of the same capacity such that the refrigerant passes in a continuous yand uninterrupted liquid mass through the restrictive device and thereafter is converted by expansion to a highly saturated, relatively wet vap or and remains as a relatively wet vapor in passing through the evaporator and accumulator to the compressor whereby substantially all the internal surfaces of the evaporator are backed with liquid refrigerant,

moving said refrigerant through the system in a condition such that a rapid transfer of heat occurs through the evaporator walls Iand the surface temperature of the evaporator is maintained relatively near the temperature of the area bein-g refrigerated so that a relatively high humidity is provided in the area being refrigerated,

insuring a continuous supply of liquid refrigerant on the high side by the use of a receiver positioned below the condenser,

and continuously accumulating and trapping liquid howing from the evaporator toward the compressor.

2. In a refrigeration system comprising a compressor, a condenser, a liquid receiver, an evaporator and an accumulator connected between the evaporator and the compressor, the improvement wherein a restrictive device is provided between the liquid receiver Eand the evaporator,

said refrigerating system being charged with at least twice vthe refrigerant used with such a system of the same refrigerating capacity,

the size of said restrictive device being such that the abnormal volume of refrigerant passes in a continuous and uninterrupted liquid mass through the restrictive device and thereafter is converted by expansion to a highly saturated, relatively wet vapor and remains as a :relatively wet vapor in passing through the evaporator yand into the accumulator,

said restrictive device comprising a tube which is shorter in length or greater in diameter than a conventional capillary tube for the refrigeration components of comparable size,

said laccumulator having a volume not less than the volume of the evaporator,

said liquid receiver having a capacity suicient to maintain the condenser substantially free of liquid at all times,

said restrictive device being in heat exchange relationship with the `interior of said accumulator.

3. The method set forth in claim 1 including the step of periodically interrupting the operation of the compressor such that hot liquid refrigerant passes through the restrictive device substantially uninterrupted and facilitates the -defrosting of the evaporator.

4. In `a Irefrigeration system comprising a compressor, a condenser, a liquid receiver, yan evaporator and an accumulator connected between the evaporator and the compressor, the improvement wherein a restrictive device is provided between the liquid receiver and the evaporator,

said refrigerating system being charged with a-t least twice the refrigerant used with such a system of the same refrigerating capacity,

the size of said restrictive device being such that the abnormal volume of refrigerant passes in a continuous and uninterrupted liquid mass through the restrictive device and thereafter is converted by expansion to ya highly saturated, relatively wet vapor an-d remains as a relatively wet vapor in passing through the evaporator and into the accumulator,

said restrictive device comprising a tube which is shorter in length ior greater in diameter than a conventional capillary tube for the refrigeration components of comparable size,

said accumulator having a volume not less than the volume of the evaporator,

said liquid receiver having a capacity sufficient to maintain the condenser substantially lfree of liquid at all times.

5. The combination set forth in claim 4 Wherein said system includes connecting means between the accumulator and the inlet of the compressor and connecting means between the outlet of the compressor and the restrictive device, said connecting means being in heat exchange relationship to one another.

References Cited by the Examiner UNITED STATES PATENTS 2,035,291 3/1936` Bauman 62-`80 2,467,078 4/ 1949 Cahenzli 62-503 X 2,482,171 9/1949 Gygax 62--511 X 2,532,452 12/1950 Hoesel 62--511 X 2,812,644 11/1957 Newman 62--344 2,859,596 ll/ 1958 Evans 62-503 OTHER REFERENCES Refrigerating Engineering, August 1948, volume 56, pages 1294133.

Journal of the A.S.R.E., January 1948, pages 55-59 and 104405.

ROBERT A. OLEARY, Primary Examiner.

W. E. WAYNER, Assistant Examiner. 

1. THE METHOD OF IMPROVING THE THERMODYNAMIC EFFICIENCY OF REFRIGERATION SYSTEMS OF THE RESTRICTIVE DEVICE TYPE AND UTILIZING A CONTINUOUS TYPE EVAPORATOR AND ACCUMULATOR WHICH COMPRISES CHARGING THE SYSTEM WITH AT LEAST TWICE THE NORMAL AMOUNT OF REFRIGERANT USED WITH SUCH A SYSTEM OF THE SAME REFRIGERATING CAPACITY, CONTINUOUSLY CIRCULATING SAID ABNORMAL VOLUME THROUGH THE SYSTEM, DECREASING THE RESTRICTIVE EFFECT OF THE RESTRICTIVE DEVICE TO AT LEAST ONE HALF OF THE STANDARD TYPE FOR AN EVAPORATOR OF THE SAME CAPACITY SUCH THAT THE REFRIGERANT PASSES IN A CONTINUOUS AND UNINTERRUPTED LIQUID MASS THROUGH THE RESTRICTIVE DEVICE AND THEREAFTER IS CONVERTED BY EXPANSION TO A HIGHLY SATURATED, RELATIVELY WET VAPOR AND REMAINS AS A RELATIVELY WET VAPOR IN PASSING THROUGH THE EVAPORATOR AND ACCUMULATOR TO THE COMPRESSOR WHEREBY SUBSTANTIALLY ALL THE INTERNAL SURFACES OF THE EVAPORATOR ARE BACKED WITH LIQUID REFRIGERANT, MOVING SAID REFRIGERANT THROUGH THE SYSTEM IN A CONDITION SUCH THAT A RAPID TRANSFER OF HEAT OCCURS THROUGH THE EVAPORATOR WALLS AND THE SURFACE TEMPERATURE OF THE EVAPORATOR IS MAINTAINED RELATIVELY NEAR THE TEMPERATURE OF THE AREA BEING REFRIGERATED SO THAT A RELATIVELY HIGH HUMIDITY IS PROVIDED IN THE AREA BEING REFRIGERATED, INSURING A CONTINUOUS SUPPLY OF LIQUID REFRIGERANT ON THE HIGH SIDE BY THE USE OF A RECEIVER POSITIONED BELOW THE CONDENSER, AND CONTINUOUSLY ACCUMULATING AND TRAPPING LIQUID FLOWING FROM THE EVAPORATOR TOWARD THE COMPRESSOR. 